Holy Smokes! You should reeeeeeeally consider upgrading. That version is so old it scares me
To add a forum, go to your Control Panel, then Forum Settings. The link to add a new one is there.
(Admins: psssst, please move this to Version 5 assistance! I don't have power to do that here <img src="https://www.ubbcentral.com/boards/images/graemlins/smile.gif" alt="" /> )